Wireless technologies such as Service Architecture Evolution (SAE)/Evolved Packet Core (EPC) technology address how a core network may be accessed via radio access technologies of various types. For example, a SAE/EPC core network may be accessed via an air interface based on a technology such as Evolved. UMTS Terrestrial Radio Access Network (E-UTRAN), Institute of Electrical and Electronics Engineers (IEEE) Wireless Local Area Network (WLAN), Code Division Multiple Access 2000 (CDMA2000), or IEEE Worldwide Interoperability for Microwave Access (WiMax).
A number of approaches have been developed to facilitate transitions between different types of radio access technologies. The Access Network Discovery and Selection Function (ANDSF), for example, is a server that stores and provides inter-system mobility policy and access network discovery information. IEEE 802.21, also referred to as Media Independent Handover (MIH), provides a framework that facilitates mobility of wireless transmit/receive units (WTRUs) between heterogeneous access networks. MIH includes an MIH information server that provides handover policies and access network information to facilitate network selection and handover decisions. Using the ANDSF and/or MIH, a WTRU may remain in communication with a core network while transitioning between access networks of different technology types.
When a WTRU transmits/receives data via a core network, it may do so by using one or more data flows. In the context of Long Term Evolution (LTE), efforts have been made to allow WTRUs to communicate by using Internet Protocol (IP) flows, which are data flows that include IP data. As an example, a WTRU may simultaneously engage in distinct IP flows related to a video telephony call, a non-conversational video stream, and a peer-to-peer (P2P) download. A single application may transmit and/or receive data related to a single IP flow or multiple IP flows. A WTRU may communicate using IP flows over multiple access networks simultaneously, and multiple IP flows related to the same application may be used over different access networks.
Although efforts have been made to facilitate the use of data flows such as IP flows in the context of heterogeneous access networks, these efforts include a number of shortcomings. For example, these efforts do not adequately address how the selective handover of data flows between access networks of different technology types, as well as other related functions, may be performed. As further examples, these efforts do not adequately address how data flows may be defined and how data used in the handover of data flows may be stored and communicated. Accordingly, new technologies are required that address the above-listed shortcomings as well as other shortcomings of the current technology.